Anode for electroplating



July 3, 1934.

H. LE LAURIN. ET Al.

ANODE FOR ELE Filed NOV. 16. 1931 CTROPLATING 2 Sheets-Sheet l nnauunhlll ,HIHIIiIlllllll'flllllllflhll July 3, 1934 H. LE LAURIN ETM1 1,964,736

ANODE FOR ELECTROPLATING Filed Nov. 16, 1931 2 Sheets-Sheet 2 zz/enm; jlfejfaara d?. l Fry Patented .telly 3, 1934 W'EDV l y meant dreien Application November 16, 1231, Seria?. No. 575,4i29

12 @latina (131. 21B/1nd) (Granted under the act of March 3, lldhas amended .dprill 3d,

Our invention relates to an improved anode for electroplating the interior surfaces of hollow cylindrical articles, such as gun barrels.

It is the object of this invention to providek an anode that may be' kept at the optimum temperature for the plating operation and that secures uniform distribution of current density over its surface, yet is simple in construction.

With the above and other objects'in view, the

invention consists in the construction, combination and arrangement of parts as will be hereinafter more fully described.

Reference is to be had to the accompanying drawings forming a part of this specification in which like reference characters indicate correspending parts throughout the several views and in which: v

Fig. l is a longitudinal section of a plating installation using our improved anode;

Fig. 2 is a transverse section on the line Fig. 1; and

3 is a transverse section on the line 3 3,

vThe copending application of P. E. McKinney and H. Le Laurin, Serial No. 578,172, filed November 30, 1931, discloses an anode of the same general type and forl the same purpose as the present l invention, over which this is an improvement.

f It has been foundthat chromium plating the bores of large caliber guns greatly increases the useful life thereof, as the plating may be renewed repeatedly and the barrel kept in serviceable condition much longer than is possible with unplated barrels. Whereas an unplated barrel is .35 good for about one hundred twenty rounds, re-

plating with chromium every sixty rounds keeps it in good condition for much longer than the usual life of one hundred twenty rounds.

The pit having walls 4 is of depth suflicient to receive a tank 5 to contain a bath in which the article to be plated, in this case shown as a gun barrel 6 for purpose of illustration. Successful plating with chromiumrequires very close control of the temperature of the electrolyte and of the article being plated (within 7 F. of the optimum), and for this purpose steam inlet pipe 7 is provided to supply steam to coil 8, from which the exhaust steam is carried away through pipe 9. Pipe 10 is to introduce water into the bath to reduce temperatures when necessary, the excess water being discharged through overow l1. Thermometer 12 may be of the recording type, and the inlet of water or steam controlled by manually operated valves, but preferably the thermometer actuates one of the well known automatic valve mechanisms so that the temperature control requires no attention.

The breech chamber of barrel 6 is not plated, and is closed by a hollow plug 13 closed at its upper end, into which is set a gasket 14 to form a tight seal. The closed end of plug 13 has apertures.15 therethrough to admit electrolyte from the interior of barrel 6 to the cavity in. the plug. After the barrel has been removed from the bath, drain valve 16 may be opened to remove the electrolyte from barrel 6. The lower end of the barrel is positioned in the bath by engaging frusto-conical plug 17 with a like shaped face in the plug 13.y In the upper face of plug 13 is set an insulating block 19 having therein a recess to be engaged by the lower end of the electrode to aid in positioning the electrode in a position such that it will be uniformly spaced from the surface to be plated.

Adjacent the upper end of barrel 6 a ring 20 is clamped thereto, and from this ring arms 21 extend radially outwardly. These arms are of such length that they move freely in tank 5 but are substantially in contact therewith to position the upper end of barrel 6 in the bath. Links 22 are provided in arms 21 to be engaged. by lifting devices to handle the barrel 6. Y

Stud bolts 23 pass through arms 2l and engage the bottom of a receptacle 24 for electrolyte in addition to that in the barrel 6, a gasket 25 between the receptacle and the barrel making a fluid tight joint. IThermometer 26 is disposed in receptacle 2d to indicate the temperature of the electrolyte.

The anode comprises a copper tube 27 that is either plated or sprayed with lead on its exterior surface to resist the action of the electrolyte. Within tube 27 and concentric therewith is a tube 28, preferably of copper, that is closed at its lower end by a plug 29 adapted to engage the recess in insulating block 19 in plug 13 and to which tube 27 is sealed.

The upper end of tube 28 is connected to a water pipe" 30 and the lower end thereof is perforated at 18 to permit water to pass out into tube 27 from which it is removed through pipe 3l. Tube 27 is placed in electrical connection with tube 28 by screws 32 in'threaded connection with the latter and with.A their heads bearing firmly against the former. Member D33 is connected to both tubes, and carries bolts 3d for binding electrical cables to the member. The tube 28 thus serves both as a conduit for coolant and as a conductor to distribute current uniformly over the surface of tube 28 to insure even deposition of the plating metal over the adjacentsurace of the barrel.

Heavy copper bands 35 clamped to barrel 6 @lll lll@

connect the barrel to bus bar 36, through which bus bar and cables 37 connected thereto the cur.

rent is conducted away from barrel 6.

The present invention is an improvement over the anode in the above mentioned copending application in that the inner current distributing member serves as a conduit for the coolant in the electrode, thus eliminating the pipes employed for that purpose disclosed in the said application, and increasing the number of points of connection between the outer tube of the electrode and the inner conducting member in this device, thus securing much more uniform current density over the suriace of the anode with resultant greater evenness of deposition of the plating metal.

Plug 13 is retained in position inbarrel 6 by bolts 37 that are connected at one end to the base of the plug and at the other end carry nuts 38 that bear against ears 39 on split ring 40` that is clamped around barrel 6.

It will be understood that the above description and accompanying drawings comprehend only the general and preferred embodiment of our invention, and that various changes in construction, proportion and arrangement of parts may be made Within the scope of the appended claims, and without sacrificing any of the advantages of our invention. l

The herein described invention may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to us of any royalties thereon.

Having thus described our invention, what we claim is:

il. In an apparatus for electroplating the interior surfaces of hollow cylinders, means adapted to close an end of such cylinders, an insulating member set into the upper part of said means, a receptacle mountable on the upper end of the article to be plated to contain electrolyte in addition to that in the article; and an anode comprising an outer tube, an inner tube disposed in said outer tube coaxially therewith, the said inner tube being perforated adjacent its lower end, a plug closing the lower end of said inner'tube and sealed into said outer tube and adapted to rest upon said insulating member, means forming an electrical connection between said two tubes at their upper ends, conducting elements connecting said two tubes at various places intermediate their ends, means to introduce a coolant into said inner tube, and means to carry away said coolant from said outer tube. 2. In apparatus for electroplating the interior surfaces of hollow cylinders, an anode comprising.,an outer tube, an inner tube disposed in said I outer tube coaxially therewith, the said inner tube being perforated adjacent its lower end, a plug in the lower end of said inner tube sealed into said outer tube, means forming a plurality of electrical connections between said tubes at their upper ends, conducting members connecting said tubes at a plurality of points between their ends, means to introduce a coolant into said inner tube, means to carry said coolant away from said outer tube, and means closing the space between said tubes at the upper end of said outer tube.

3. An anode for electroplating the interior surfaces of hollow cylinders, comprising an outer tube, an inner tube disposed in said outer tube coaxially therewith, said inner tube being peri'orated adjacent its lower end, means forming a closure for said lower end and to which the lower edge of said outer tube is secured, means forming electrical connection between the upper ends of said tubes, means connecting said tubes together at a plurality of points intermediate their ends, and means for circulating a coolant within and around said inner tube.

4. An anode for electroplating the inner sur- Lacasse faces of hollow cylinders, comprising an outer tube, an inner tube disposed in said outer tube coaxially therewith, means forming a closure for the lower end of said inner tube and to which the said outer tube is electrically connected, means electrically connecting said tubes together at a plurality of points intermediate their ends, and means including said inner tube for circulating a coolant within said outer tube.

5. A substantially cylindrical anode, comprising inner and outer hollow conducting members electrically connected together at a plurality of points throughout their length, the said inner member forming part of a circulating system to carry coolant other than the electrolyte of a bath in which saidanode may be used.

6. A substantially cylindrical anode, comprising an elongated hollow member, means closing one end of said member, means in said member to introduce a temperature controlling substance thereinto adjacent said closed end, means to convey away said substance from the other end of said member, and means electrically connecting together said member and said iirst mentioned means at a plurality of points throughout their length.

7. A substantially cylindrical anode, comprising an elongated electrically conducting hollow member, means for introducing temperature controlling substancethereinto adjacent one end, means for conveying awaysaid substance from the other end, and means electrically connecting said member and said rst mentioned means' together at a plurality of points throughout their length.

8. An electroplating anode, comprising an elongated hollow member, a second hollow member therewithin extending substantially throughout the length of said iirst mentioned member, and electrically conducting means forming a closure for one end of both of said members, said second member being adapted to discharge a temperature controlling substance into said first hollow member adjacent said closure.

9. An electroplating anode, comprising a hollow member and an element therein serving to define passages for circulating a temperature controlling substance other than the electrolyte of a bath in which said anode may be used and to provide means `for securing uniform current distribution over said member.

10. An electroplating anode, comprising a hollow member, and a second member substantially symmetrically disposed therein serving to aid in securing uniform current distribution of said member and to carry a cooling substance other than the electrolyte of a bath in which sai anode may be used.

11. An electroplating electrode, comprising a main portion and a second portion serving to aid in circulating temperature controlling substance other than electrolyte in said main portion ,and also in securing uniform current distribution thereover.

12. An electroplating electrode, comprising a main portion and a second portion for circulating a temperature controlling substance other than electrolyte in said main portion, said portions being substantially coextensive throughout and of substantiallythe same shape.

HARRY LE LAURIN. ALBERT L. FRY. 

